Scanning apparatuses are widely used for scanning images of paper documents. Consequently, the contents of the paper documents can be converted into electronic files. The electronic files may be further spread, managed or stored by the user. Conventionally, the scanning apparatus may acquire the complete image of the document by linearly scanning the document. That is, when the document is driven to be transferred through an immobile scanning module at a constant speed, a scanning operation is performed on the document. Alternatively, for performing the scanning operation, the scanning module is moved from an end of the document to the other end of the document at a constant speed while the document is kept immobile. The above scanning approaches are well known to those skilled in the art, and are not redundantly described herein.
The conventional scanning apparatus, however, has some drawbacks. For example, if the user wants to acquire a complete image of a document, it takes a time period of waiting for the document to be completely transferred through the scanning module or waiting for the scanning document to be completely transferred through the document. Since this time period is relatively long, the scanning efficiency of the conventional scanning apparatus fails to meet the requirements of the modern societies. Moreover, the image quality acquired by the conventional scanning apparatus is dependent on the transmitting speed of the document or the moving speed of the scanning module. If the transmitting speed of the document or the moving speed of the scanning module is not kept constant, the acquired resultant image may be discontinuous. In other words, it is difficult to control the conventional scanning apparatus.
For solving these drawbacks, a document image reading apparatus has been disclosed in for example U.S. Pat. No. 5,805,272. FIG. 1 is a schematic partial front view illustrating a conventional document image reading apparatus disclosed in U.S. Pat. No. 5,805,272. In the document image reading apparatus 1, an image pickup device 11 is disposed over a document table 12. The complete image of an inside page of a book 3 placed on the document table 12 may be directly acquired by the image pickup device 11 in an area scanning manner. The way of acquiring the image by the image pickup device 11 in the area scanning manner is similar to the way of acquiring the image by the conventional camera.
Moreover, a sheet transfer channel 13 is disposed under the document table 12. Each of the single documents P1 placed on a sheet output tray 14 may be fed into the sheet transfer channel 13, and then transmitted to a document image reading section 15 at the middle of the document table 12. Consequently, the image of the document P1 is shot by the image pickup device 11. However, since the area of the document image reading section 15 is very small, only a portion of the image of the document P1 is acquired at each shooting time. For acquiring the complete image of the document P1, the document P1 should be shot at multiple times during the process of moving the document P1.
From the above discussions, if the user wants to use the document image reading apparatus 1 to read the complete image of a single document at a shooting time, the document needs to be manually placed on the document table 12 in order to be shot by the image pickup device 11. However, if a great number of documents need to be read, the documents should be sequentially and manually placed on the document table 12 in order to be shot by the image pickup device 11. In other words, the document image reading apparatus 1 is not user-friendly. Moreover, if the document image reading apparatus 1 is employed and the automatic document feeding function of the document image reading apparatus 1 is enabled to acquire the images of all documents, the drawbacks from the manual operation may be eliminated. However, the time period required to read the image of each document is increased.
From the above discussions, the conventional scanning apparatus needs to be further improved.